1. Field of the Invention
The invention relates to a memory device, and more particularly, to a memory device having U-shaped dielectric layer between floating gate and substrate.
2. Description of the Prior Art
A flash memory is a type of non-volatile memory, which can preserve data within the memory even when an external power supply is off. Recently, because flash memories are electrically re-writable and electrically re-erasable, they have been widely applied in the fabrication of electrical products, such as mobile phones, digital cameras, video players, personal digital assistants (PDA) or systems on a chip (SOC).
However, issues such as encroachment in oxide-nitride-oxide (ONO) stack and tunnel oxide layer is often observed during the fabrication of flash memory thereby affecting the operation and performance of the entire device substantially. Hence, how to improve the architecture and process of current flash memory thereby improving the endurance of the device has become an important task in this field.